Magnetic heads are provided in computers for transferring information between the magnetic heads and storage media such as discs disposed in contiguous (almost abutting) relationship to the heads. The magnetic media such as the discs are rotated by disc drives under the control of microcomputers to particular positions where the transfer takes place. When the transfer is from the disc drive to the magnetic head, the information read by the magnetic head is processed in the microcomputer and the processed information is then transferred from the head to a storage position in the disc. The information transferred between the head and the disc is generally in binary form.
The rate of transferring binary information between the head and the storage medium such as the disc has been progressively increasing through the years. In order to transfer such information at progressively increasing rates, the size of the heads has been progressively decreased. Furthermore, as the size of the heads has progressively decreased, the precision in the manufacture of parts in the head has had to progressively increase in order to be able to transfer the binary information accurately between the head and the disc drive at the increased rates.
The magnetic heads include members which face the magnetic discs and protect the magnetic heads in case the magnetic discs should crash against the magnetic heads as the discs rotate at high speeds. These members may be made from a suitable insulating material such as an aluminum oxide with an index of refraction of at least 1.63 to provide the members with hard and dense characteristics. These members have decreased in size in accordance with the decrease in size of the heads. Furthermore, the dimensions of these members have had to become more precise as the size of these members has decreased and as the rates of transfer of the magnetic information between the heads and the discs have increased because of the rotation of the discs at increased speeds and because of the decreased size of these members. These members have been formed as die on a substrate.
Even as the size of the die on the substrate has tended to decrease through the years, the size of the substrate has tended to increase. As the size of the substrates has tended to increase, it has become progressively difficult to fabricate the members on the die with great precision. For example, when the substrate has a width of approximately six inches (6"), hundreds, if not thousands, of the members may be simultaneously produced on the substrate. Any slight deviation in dimension (e.g. thickness) at one end of the substrate may become magnified in die which are progressively disposed on the substrate toward the other end of the substrate.
The substrates are often fabricated on a one-at-a-time basis in processing equipment. As will be appreciated, this fabrication is relatively slow even though there may be hundreds, if not thousands, of die on a single substrate. Processing equipment also exists for directing a plurality of substrates in sequence through a plurality of successive stations. Although this may be considered to constitute an improvement from a time standpoint, it still provides a processing of only a single substrate at any one time at each successive processing station.
It is desirable to process a plurality of substrates simultaneously to provide a deposition on each of the substrates with the same parameters. For example, it is desirable that the thickness of the deposition on each die be substantially uniform at different positions on the die. It is also desirable to process each of the substrates in the plurality simultaneously with great precision (e.g. substantially uniform thickness) in each of the successive processing steps. This desirability of being able to process a plurality of substrates simultaneously with great precision has been recognized for some time but no one has been able to accomplish this until now. This has been particularly true in fabricating substrates each of which has hundreds, if not thousands, of die for use as members in magnetic heads.
It is further desirable to provide one (1) apparatus which operates on an automatic basis to process simultaneously a plurality of substrates from the steps of receiving the substrates from a cassette module to the steps of positioning the substrates on planets and then to the steps of providing controlled depositions on the planets. It is further desirable to provide apparatus which operates on an automatic basis to return the substrates to the cassette module after the controlled depositions on the substrates.
Co-pending application 08/554,459 filed on Nov. 7, 1995, now U.S. Pat. No. 5,830,272, in the name of Robert George Begin and Peter J. Clarke for a "SYSTEM FOR AND METHOD OF PROVIDING A CONTROLLED DEPOSITION ON WAFERS" and assigned of record to the assignee of record of this application discloses and claims a system for, and method of, providing controlled depositions simultaneously on a plurality of substrates. The system and method disclosed and claimed in co-pending application 08/554,459 also provide the controlled depositions simultaneously on the substrate with great precision (e.g., substantially uniform thickness). The system and method disclosed and claimed in U.S. Pat. No. 5,830,272 are also advantageous in that they are able to provide the controlled depositions simultaneously on the substrates, even when the substrates have square rather than round configurations, with great accuracy and at fast rates. The controlled depositions are able to be provided simultaneously on the substrates after precisely positioning the substrates so that the successive die are substantially parallel longitudinally and laterally to the walls defining the peripheries of the substrates.
In one embodiment of the system and method disclosed and claimed in U.S. Pat. No. 5,830,272, a robotic arm assembly in a transport module is expansible to have an effector at its end receive a substrate in a cassette module. The robotic arm assembly is then contracted and rotated with the effector to have the effector face a process module. Planets on a turntable in the process module are rotatable on first parallel axes. The turntable is rotatable on a second axis parallel to the first axes to move successive planets to a position facing the effector. At this position, an alignment assembly is aligned with, but axially displaced from, one of the planets. This assembly is moved axially into coupled relationship with such planet and is rotated to a position aligning the substrate on the effector axially with such planet when the arm assembly is expanded.
A lifter assembly aligned with, and initially displaced from, such planet is moved axially to lift the substrate from the effector in the system disclosed and claimed in U.S. Pat. No. 5,830,272. The arm assembly is then contracted, rotated with the effector and expanded to receive the next cassette module substrate. The lifter assembly is then moved axially to deposit the substrate on the planet. When the substrates have been deposited on the planets as described above, the planets are individually rotated on the first axes by the turntable rotation on the second axis with the stator braked. Guns having a particular disposition relative to the planets provide controlled depositions on the substrates during such planet rotations. The planets and the effector hold the substrates at peripheral positions displaced from the controlled substrate depositions.